


incubation

by gooey_boop



Category: Undertale (Video Game)
Genre: Alternate Universe - Undertail (Undertale), Begging, Forced Orgasm, Forced Pregnancy, Fucking Machines, I think that's it - Freeform, Non-Consensual Bondage, Non-Consensual Drug Use, Non-Consensual Touching, Other, Oviposition, Rape, Sanster, Sex Toys, Torture, yeah it's going there
Language: English
Status: Completed
Published: 2020-11-20
Updated: 2020-11-20
Packaged: 2021-03-10 06:27:17
Rating: Explicit
Warnings: Rape/Non-Con
Chapters: 1
Words: 2,538
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/27638855
Author URL: https://archiveofourown.org/users/gooey_boop/pseuds/gooey_boop
Summary: gaster attempts to see how much a magic-based monster can incubateand sans was just kinda at the wrong place at the wrong time so he's who gaster is testing onbig oof
Relationships: W. D. Gaster/Sans
Comments: 2
Kudos: 57





	incubation

**Author's Note:**

> so this story was based on this beautiful image by McLeech - https://twitter.com/LeechMc/status/1293022331393019909
> 
> thank you for letting me write with this as inspiration!

“ _ Sans” _

The small skeleton shifted sleepily; he was just getting comfortable

“Sans”

Who was that? Did it matter? Probably not, he was just about to take his nap, and that was much more important.

“Sans! God, get up!”

Sans snapped upwards, papers flying off his desk as a disembodied hand grabbed him by the back of his lab coat and jerking him up. “Ah! God! Shit sorry” Sans yelped as he was tugged to his feet, tripping over himself and falling to his knees.

He looked up, chuckling awkwardly as Gaster stared down at him “you are pathetic, Sans” he stated flatly as Sans pulled himself back up. “Yeah yeah, I’m aware” he snickered, stuffing his hands into his pockets “whatcha need doc?” 

Gaster sighed and rolled his eyes “I need help with a particular experiment. Despite your incompetence I believe you are the perfect candidate” he said, walking out of Sanses office and down the hall, the smaller skeleton quickly following after. “Soo, what is this experiment?” Sans asked, bumping into Gaster as he stopped midstep. “Unimportant,” he said, grabbing Sans by the shoulder and pulling him forward swiftly. 

A bright light flashed and filled up the room, Sans stumbling forward as Gaster jumped through the void. “Dude! Tell me before you do that” Sans hissed as he almost fell on his face. He looked up at Gaster and could have sworn he saw a pleased smile. “Oops,” he said, then started walking down one of the halls. Sans scrambled to catch up, glancing around as he went.

The long halls were dark and the floor rumbled slightly. “What is this place?” he asked, his words echoing against the wall. “This is my personal lab. In here please,” Gaster said, opening a door, the hinges creaking as Sans walked in, sitting in a chair as Gaster motioned to it. He opened a cabinet and took out a bottle of pills, filling a glass with water and handing them both to Sans. “Take that please,” he said, fishing through the draws for something. Sans shrugged and popped the pill into his mouth, taking a gulp of water. “What’s this for?” he asked, finishing the water and setting it down. 

“I intend to test the viability of capacity for germination in magic based monsters,” he said, fiddling with the batteries. Sans stared at him for a second, raising his brow. “I understood 3 of those words,” he said as Gaster slipped the recorder into the pocket of his lab coat. “That’s expectable,” Gaster said “you are extremely well versed in technology but that’s where your vocabulary ends. Take off your clothes.”

Sans nodded for a second, then did a double-take. “I’m sorry what?” he asked, freezing in slight shock. “Remove your clothes,” Gaster said, and Sans flushed blue. “W-wow” he laughed “if you wanted to have some fun we could have gone to my place~”. Gaster rolled his eyes as Sans stripped, one of his hands floating over and picking up his lab coat. 

“You can keep this,” he said, dumping it into Sanses arms “follow me.”

Sans slipped on the coat and pulled it around his waist, following Gaster back into the hall. He pulled out a keycard and pressed it against a keypad next to a heavy metal door. He pulled it open with a heave, motioning sans in. 

Sans walked in backward, a big grin on his face “so doc, this your room?” he chuckled and turned around, his smile quickly falling.

In the middle of the room, sat a large machine.

The main body of it was a maroon metal, almost a cylinder with an opening at the front. At the top of the inside of the cylinder was a funnel contraption, and that was connected to two large glass containers filled with small green beads. “W-wait a minute” Sans croaked, taking a step back “wait a minute” 

Sans jerked as one of Gaster’s hand constructs grabbed him by the wrist and dragged him towards the machine, Sans flinching as the heavy door slammed shut. “Wait wait wait” Sans squeaked, trying to wrench his arm free, only for more hands to grab onto his limbs “what are you doing!?”.

He struggled wildly as he was lifted inside the cylinder. He was turned upsidedown, his ankles towards the top of the machine. He kicked out as the hands slipped his legs into rubber sleeves, pulling them up to his shins and pulling them tight with leather straps around the top. 

“Stop it! God damn it what are you doing?! Let me go asshat!” Sans screamed, Gaster ignoring him. Sanses’ arms were pulled away from his body and straight outwards. They were slipped into similar sleeves, ending just after his elbows. the hands rolling up his sleeves and cinched them tight.

“Current time, 1708. Subject has been restrained” Gaster spoke into his recorder “extreme negative reaction. May administer a small dose of sedative”. Sans pulled and thrashed against his restraints, only managing to strain his joints. His coat fell down past his back, exposing him completely. He cried as a hand grabbed his chin, yanking his head back as a needle was jammed into his neck between his vertebrae.

“Starting body summoning attempt; method 1. Drugs have been administered to aid formation” Gaster stated, clicking the recorder off. Sans yelped as a construct pressed against his pubic symphysis, rubbed the sensitive notch between the thumb and forefinger. He choked on a gasp as more hands massaged down his femurs and the base of his spine. 

“Relax, Sans,” Gaster said as he twisted and tried to pull away. “Relax my ASS!” he screamed, “what are you doing? Stop touching me! Let me go!”. Sans moaned as gaster hit just the right spot, biting his tongue in horror at the reaction. “Here?” he asked, Sans growling and choking as the hand bore down persistently at the same spot, making him squeak and gasp.

His soul fluttered behind his chest, illuminating the inside of his ribs. “Soul attempting to manifest. Continuing stimulation.”

Sans cried out as a hand dipped inside his ribcage, rubbing a finger down the underside of his sternum. His soul flickered again, dimming slightly as it settled behind his chest. The hand in his chest pulled out as a layer of ecto bloomed out from his chest, forming down his torso and thighs.

“Body formed. Continuing to next step. Subject still expressing strong resistance. Sedative dose has not set in yet.” Gaster said, directing one of his constructs to slide down Sans slit, making him gasp and whine. The fingers dipped in shallowly, rubbing loose circles around his clit. “Body beginning to lubricate,” Gaster said, as light blue slick coated his fingers. Sans moaned softly as the hands pulled away, looking up with horror as he watched them move the funnel above his entrance. 

“W-ait” he begged as Gaster walked to a control panel at the side of the room “Gaster please, we can talk about this”. Gaster ignored him and pressed a series of buttons, the machine started to hum mechanically and the funnel lowered slowly, Sans twisting frantically as the hands held his entrance open. He cried as the cold material slid into his entrance with a slick pop. it pressed down further into Sans, stretching him past the point of comfort. He wanted to vomit as he saw it through the transparent flesh

“Deposition device inserted. Turning on main power”.

Sans whined as Gaster pushed a large button on the control panel and the machine started clunking slowly.

Cha-clunk

Cha-clunk

Sanses eyelights were blown out as the drug started taking effect. “Releasing incubation fluid,” Gaster said, pressing another button “sedatives seem to have started to take effect”.

Sanses eyes widened and he groaned as warm fluid surged from the tip of the funnel, gushing into his stomach. It belled out over his pelvis, bulging out as pressure built inside of him. He cried softly as the fluid slowed and eventually stopped. 

“Sufficient fluid build-up. Continuing to next step” Gaster turned a nob slowly, a small valve under each jar opening. Sans whimpered as the small green beads slid down tubes and disappeared into the funnel.

His eyes widened as he watched a single bead slide out of the tip. it floated lightly through the fluid in his stomach, before settling against the gel. “W-what are you doing?” Sans cried “what is that?!”. He twisted his legs as hard as he could, cringing as his kneecaps scraped against his bones. 

Gasters hands grabbed onto his thighs, holding him still as another bead popped out of the machine. “I told you already, but I guess I could dumb it down a little” Gaster said, sitting in a spinny chair and turning towards Sans “so far, you have been filled with a nutrient-dense fluid. I intend to test how many eggs your body can incubate before rejecting.”

Sans cried as snot dripped down his face, letting the words sink in. “e-eggs?” he gasped “eggs!?”. Gaster sighed and took out his recorder. “About 10 minutes after experiment started. Explained basic purpose to subject, resulting in an extremely negative reaction. Will attempt to further explain to calm him down slightly,” Gaster said, then clicked it off. 

“They aren’t  _ technically _ eggs,” he said “they are gelatin beads with computer chips. As I said, I want to test if you can be used as a suitable host. This is a test run; I would not waste my more valuable resources until I’m certain this will work” he chuckled to himself “my materials are expensive. It would be easier just to get another subject if you prove to be ineffective. no offense.” 

Sans whined loudly as another egg was deposited; he could feel it sliding into his passage and into his stomach. “Subject seems to have calmed slightly. Turning up speed” Gaster said, turning up the dial. 

Sans cried as the funnel swelled, the plastic straining against his magic. He watched in terror as the tubes filled with eggs, dripping into him at a steady pace. As more of them were inserted the weight of them became more apparent. His walls convulsed around the funnel, Gaster frowning as a finger drew across his swollen labia making him flinch. He turned back to the controls and fiddled with a few nobs. “Subjects body seems to have stopped self-lubrication. Attempting to aid arousal” he said, one of the hand constructs moving from his thigh up to his clit. 

Sans yelped as a finger pressed hard against the sensitive nub, moving in slow, steady circles. Tears dripped off his face as he trembled, jerking against his restraints. With a soft moan, Gaster slipped a finger in beside the funnel, rubbing softly against the ridges of his walls. The stretching was uncomfortable, but the gentle touches were better than hard plastic. 

“Hngg please” Sans whined as he fell limp, Gaster still bearing down mercilessly against his clit. “The more you resist the worse it will get,” Gaster said calmly and turn on the recorder; “machine still showing resistance. Perhaps the subject still isn’t wet enough? Will aid through climax before moving to next speed”. 

Sans bit his tongue, moaning loudly as tears streamed down his face. He was dying. Dear god he was dying. “Gaster!” he gasped, trying to breathe through his sobbing “p-please t-turn it off!”. His hips jerked forward painfully as Gaster tightened his circles. Two more eggs pushed past the funnel and drifted to the pile that was building up in Sanses stomach. His thighs trembled as the coil inside him broke, cyan slick coating the funnel and gasters hands. “Climax achieved. Moving to next speed setting,” Gaster said, twisting the dial again.

Sanses eyes widened and he screamed, hands immediately clutching at his thighs and torso. “Calm down, Sans,” Gaster said, nearly inaudible over Sanses shrieks and sobs. The tension in his stomach was becoming unbearable, pain thrumming through his body. “P-lease! P-p-please s-s-top” he begged, twisting and pulling until his elbows popped out of place, but the hands held him steady. 

Gaster sighed and rubbed his nasal ridge. “Subject still extremely resistant. I am considering ending this sensation early-” he was interrupted by a wail “YES! Yes please make it stop!” Sans begged. Gaster frowned “you are being unreasonable” he criticized “how about this; you take 10 more while staying quiet, and we can stop here for today. OR you can continue to act like a child and I’ll leave you here until you are puking them out as fast as they go in.”

Sans gasped and sputtered as he tried to calm his breathing “o-ok” he sobbed, breathing with his chest to keep himself quiet. “Good boy,” Gaster said clicking the recorder “made a deal with the subject. He seems to have calmed.” he clicked it off as the hands on Sanses body loosened slightly. 

Sans cringed, squeaking as another egg slipped in. “good. That’s one” Gaster said, standing from his chair and going over to a cabinet and pulling it open. Sans whined loudly as two more pushed in at the same time. Gaster looked back at him “that’s three? Remember to stay quiet”.

Sans let out a shaky deep breath; Gaster pulled a thick plug from the cabinet and brought it to the sink, washing it off. Another one and tears slid down Sanses face, biting his tongue to muffle himself. Now that he was calmer, the feeling of the squishy beads pressing against his walls, then the slight  _ pop _ when they floated down into the pile was even more pronounced. “Good,” Gaster said, one of his hands sliding down and palming Sanses stomach, another one massaging down his thighs “that’s it~”

Another and another; each one felt like an eternity. Sweat and tears dripped to the floor as Gaster sent a hand to press a button on the control panel. The mechanical hum of the machine slowed and eventually stopped. With another press of a button, the funnel raised up, the hands guiding it up. Sans whined as a small bit of the fluid slipped out of him, then his passage tensed up, effectively sealing it in. “quiet” Gaster reminded, a hand floating the plug up to Sans, and worked it into his passage, a large knot locking it deep inside Sans. “That’s it, now stay still,” he said unbuckling the straps and slipping Sanses limbs out of the sleeves. “session has been ended early. Administering a second, stronger dose of sedative” he said into the recorder. Sans keened softly as a needle was worked into his neck. One of the hands ran down his arm and prodded at his dislocated elbow “subject seems to have hurt left arm in restraints. I will look at this once he is unconscious”.

Gasters hands carried Sans down from the machine, turning him right side up. He moaned softly as the eggs shifted to a new position. His head lolled to the side as snot and drool dripped down his face. He was barely conscious as he was caring out of the room, on hearing Gasters last report before his eyelights fuzzed out.

“Will attempt another session in 24 hours”


End file.
